[3H]nisoxetine: a new radioligand for norepinephrine uptake sites in brain.

[3H]Nisoxetine binds with high affinity (Kd = 0.7 nM) and selectivity to a homogenous population of sites associated with the uptake of norepinephrine. Specific [3H]nisoxetine binding to rat cortical homogenates was saturable, sodium-dependent and averaged 90% of total binding at its Kd concentration. Pretreatment with the neurotoxin DSP-4 resulted in 95% decrease in binding. [3H]Nisoxetine exhibits superior properties to radioligands previously used and appears to be the radioligand of choice for studies involving uptake sites for norepinephrine.